The NMS Agent runs on each NMS Services server and is responsible for monitoring NMS back-end services and reporting their state to the NMS Monitor module. In a dual-environment configuration, both administrative users will have an NMS Agent instance.

The NMS Monitor runs on a WebLogic managed server at each site and is responsible for periodically requesting the current status of the site from the NMS Agents, WebLogic managed servers and databases, storing the status of the sites in a ZooKeeper cluster, coordinating with other NMS Monitors in the system, determining the state of each site and triggering automatic failover and recovery of the system.

The CESEJB and NMS-WS deployments provide REST APIs to allow the NMS Monitor to request the current status of the deployment.

The WebLogic servers are used to deploy the NMS Monitor. An NMS Monitor managed server is installed on each WebLogic instance. The WebLogic Admin Server reports the state of all managed servers and their applications to the NMS Monitor.

The NMS Monitor interrogates the databases to determine the active and staging environment for each site.

An Apache ZooKeeper cluster is used to store the site status information collated by each of the NMS Monitors allowing each monitor to see the complete state of all NMS sites in the system in order to make an intelligent decision on the best disaster recovery plan to execute.